PROJECT ABSTRACT Role of regulatory T cells in adverse pregnancy outcomes after ischemia reperfusion injury Acute kidney injury (AKI) is increasingly prevalent worldwide, affecting an estimated 1 in 5 adults under hospital care. Recovery mechanisms from AKI, are not fully understood, and current markers for AKI recovery, including serum creatinine, may misrepresent recovery status. There is increasing evidence that AKI patients have lingering subclinical injury after AKI, despite serum creatinine values returning to normal, as AKI patients have higher mortality rates than patients without AKI. A recent clinical study reported that women with a history of AKI have poor maternal and fetal outcomes during pregnancy, suggesting that subclinical injury after AKI leaves these patients unable to cope with the increased renal demands of pregnancy. The goal of this proposal is to address the critical gap in knowledge regarding the mechanisms by which AKI predisposes females to adverse pregnancy outcomes using ischemia reperfusion (IR) injury as an experimental animal model of AKI. In the current studies, we propose that regulatory T cells (Tregs) act as a critical link between AKI and poor pregnancy outcomes. Our central hypothesis is that subclinical injury after IR inhibits expansion of Tregs during pregnancy, which limits nitric oxide bioavailability and results in poor maternal and fetal outcomes. Our hypothesis is supported by strong preliminary data showing that despite allowing 1 month of recovery following IR and return of plasma creatinine to basleline values, female Sprague Dawley rats have significantly smaller pups and higher rates of fetal demise compared to time-control rats that received sham surgery. Furthermore, Tregs fail to increase during pregnancy in rats after IR injury, compared to the significant rise observed in healthy pregnancy. Our central hypothesis will be tested by 3 aims: Aim 1 will test the hypothesis that failure to upregulate Tregs in pregnancy contributes to the adverse pregnancy outcomes after IR injury. Aim 2 will test the hypothesis that reduced renal reserve after IR results in uremia in pregnancy, and that the build-up of waste products with uremia inhibits Treg expansion. Aim 3 will test the hypothesis that impaired NO bioavailability after IR injury results in endothelial dysfunction and impaired uterine perfusion. The proposed studies will improve scientific knowledge by providing the necessary pre-clinical foundation to elucidate the immune cell mechanisms for adverse pregnancy outcomes after AKI and potentially identify novel immune targets.